Isolator circuit including a voltage regulator
An apparatus includes a regulator circuit that generates a voltage in response to an input current being supplied to an input terminal and functional circuitry, powered by the voltage generated by the regulator circuit. The functional circuitry, e.g., an oscillator, generates a signal using the generated voltage, the signal indicative that the current is being supplied to the apparatus. The signal can be provided over an isolation link to provide a control signal for controlling a high voltage driver circuit.
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This application claims benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 60/946,064, filed Jun. 25, 2007, entitled “Isolator Circuit Including a Voltage Regulator,” and naming as inventors Donald E. Alfano, Timothy J. Dupuis, Zhiwei Dong, and Brett E. Etter, which application is incorporated by reference herein in its entirety.
BACKGROUND1. Field of the Invention
This invention relates to isolation technology and more particularly to isolators providing isolation between a control signal and a driver circuit.
2. Description of the Related Art
Opto-isolators have been used with driver circuits to provide isolation between the control signal and the drivers. An example of a traditional opto-isolator is shown in
One problem with the opto-isolators shown in
Thus, it would be desirable to provide improved isolation technology with greater immunity to input common mode transients and improved operating efficiency.
SUMMARYAccordingly, in one embodiment an apparatus is provided that includes a first circuit including a regulator circuit configured to generate a voltage in response to an input current being supplied to an input terminal. Functional circuitry, powered by the generated voltage, is configured to generate a signal using the generated voltage, the signal indicative of the input current being supplied to the apparatus. An isolation circuit is responsive to the signal to supply a representation of the signal across an isolation barrier to an isolation link.
In an embodiment, the input current is indicative of a control signal for a driver circuit electrically isolated from the input current by the isolation barrier.
An embodiment includes a first unit that includes the first circuit, the functional circuitry and the isolation circuit. A second unit includes a receiver circuit and a high voltage driver circuit. The first unit and the second unit are coupled by the isolation link, and the representation of the signal is provided to the second unit over the isolation link, the representation of the signal indicative of a control signal for the high voltage driver circuit.
In an embodiment, the isolation circuit includes a transformer, and the transmitter circuit, when supplied with the voltage, is responsive to supply the signal into a primary winding of the transformer to cause energy to be coupled into a secondary winding of the transformer, the isolation barrier being disposed between the primary and secondary windings.
In an embodiment, when no current is supplied to the input terminal, substantially zero voltage is generated by the regulator circuit and the signal is not supplied by the functional circuitry.
In an embodiment, the first circuit is configured to be resistant to electrostatic discharge. In an embodiment, the functional circuitry comprises an oscillator circuit configured to supply the signal.
In an embodiment, a method is provided that includes receiving an input current on an input terminal; generating in a regulator circuit a supply voltage for functional circuitry using the input current; generating a signal in the functional circuitry indicative of presence of the input current using the supply voltage; and supplying a representation of the signal across a voltage isolation barrier to an isolation link.
In an embodiment, supplying the representation of the signal across the voltage isolation barrier comprises supplying the signal into a primary winding of a transformer to cause energy to be coupled into a secondary winding of the transformer, the primary and secondary windings being separated by the voltage isolation barrier.
In an embodiment, the method includes providing an electrostatic static discharge resistance as part of the regulator circuit.
The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings.
The use of the same reference symbols in different drawings indicates similar or identical items.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)Referring to
Each of the transformers is comprised of a primary 227 and a secondary 229. The primary 227 is driven with the input signal and energy associated therewith is coupled across a high voltage isolation barrier from the primary 227 to the secondary 229 and onto the transmission line 205. Energy from the transmission line is coupled from the primary winding 229 to secondary winding 227 across another high voltage isolation barrier in die 203 separating the primary and the secondary windings. The transmit circuitry 211 and receive circuitry 215 and the transformers 206 and 208 are fabricated on integrated circuits such that the primary 227 and secondary windings 229 are both formed utilizing conventional processing techniques on, e.g., separate metal layers of the integrated circuits using available conductive layers that may be shared with the transmit and receive circuits, with the high voltage barrier being formed by the separation of the conductive layers with non-conductive material formed therebetween in accordance with conventional processing techniques. In an exemplary embodiment, the high voltage barrier can provide voltage isolation of several thousand volts, e.g., up to around five thousand volts.
The die 201 includes two pins 217 and 219 that correspond to the anode and cathode in
Once the signals are received at die 203, the receive circuitry 215 detects the transmission from the first die and based on that transmission, turns on the driver 223. In an embodiment, the transmitter generates an oscillating signal when the current is present. In embodiments, the transmitter may use frequency modulation techniques or amplitude modulation techniques for the transmitted signal. An exemplary waveform driven into the primary winding 227 of transformer 206 is shown in
Referring to
In addition to providing a regulator, another design goal is to provide a circuit that is resistant to electrostatic discharge (ESD). As is known in the art, ESD, which can be several thousand volts, can lead to damage of electronic components. Accordingly, it is desirable to provide protection circuits on input terminals that make the device resistant to ESD problems. Referring to
Referring to
In embodiments in which an oscillating signal is transmitted, any circuit that can detect the presence of an oscillating signal can be used in the receive circuitry. One such example is shown in
While the single-ended isolation link shown in, e.g.,
Use of the isolation techniques described above allows the isolator to provide switching characteristics that are substantially independent of the strength of the current. In addition, by using transformer isolators, the susceptibility of opto-drivers to common mode input transients is avoided. Additionally, improved efficiency may be provided when the control current is turned off in view of the absence of resistor 111 (
While the specific transformer isolation techniques described above may be used in various embodiments of the invention, the invention is not restricted to those particular isolation techniques. In fact, many different isolation techniques may utilize the regulator approach and the regulator/ESD approach described herein.
For example, as shown in
For example, as shown in
In order to supply power for the negative going pulse in the embodiment shown in
Referring now to
Still another approach to isolation between a driver 1104 and a detector 1106 is illustrated in
Thus, while one isolation technique may use the transformer isolation technique shown, e.g., in
Although various embodiments have been described in detail, it should be understood that various changes, substitutions and alterations can be made therein without departing from the scope of the invention as defined by the appended claims.
Claims
1. An apparatus comprising:
- a first circuit including a regulator circuit configured to generate a voltage on a first power supply node in response to an input current being supplied to an input terminal coupled to the first power supply node;
- functional circuitry, powered by the voltage and configured to generate a signal using the voltage, the signal indicative of the input current being supplied to the input terminal; and
- an isolation circuit responsive to the signal to supply a representation of the signal across an isolation barrier to an isolation link.
2. The apparatus as recited in claim 1 wherein the input current is indicative of a control signal for a driver circuit electrically isolated from the input current by at least the isolation barrier.
3. The apparatus as recited in claim 1 further comprising:
- a first unit comprising the first circuit, the functional circuitry and the isolation circuit;
- a second unit comprising a receiver circuit and a high voltage driver circuit; and
- wherein the first unit and the second unit are coupled by the isolation link, wherein the representation of the signal is provided to the second unit over the isolation link, the representation of the signal indicative of a control signal for the high voltage driver circuit.
4. The apparatus as recited in claim 1 wherein the isolation circuit includes a transformer and wherein the functional circuitry, when supplied with the voltage, is responsive to supply a signal into a primary winding of the transformer to cause energy to be coupled into a secondary winding of the transformer, the isolation barrier being disposed between the primary and secondary windings.
5. The apparatus as recited in claim 1 wherein when no current is supplied to the input terminal, substantially zero voltage is generated by the regulator circuit and the signal is not supplied by the functional circuitry.
6. The apparatus as recited in claim 1 wherein the first circuit is configured to be resistant to electrostatic discharge.
7. The apparatus as recited in claim 1 wherein the regulator circuit comprises:
- first and second transistors serially connected at a first node, a gate of the first and second transistors connected to the first node, one of the first and second transistors being an N-channel transistor and one of the first and second transistors being a P-channel transistor, the first and second transistors coupled between the input terminal and a terminal coupled to supply an output current.
8. The apparatus as recited in claim 1 further comprising an integrated circuit having a two terminal interface, including the input terminal for receiving the input current and a second terminal coupled to the first circuit for supplying an output current, the integrated circuit further including the functional circuitry and the isolation circuit.
9. The apparatus as recited in claim 1 wherein the signal is an oscillating signal supplied while the input current is being supplied.
10. The apparatus as recited in claim 9 wherein the functional circuitry comprises an oscillator circuit configured to supply the signal.
11. The apparatus as recited in claim 1 wherein the regulator circuit includes a shunt voltage regulator configured to generate a substantially stable regulated voltage as the voltage.
12. The apparatus as recited in claim 1 wherein the voltage remains substantially stable over a large swing of the input current supplied to the input terminal.
13. The apparatus as recited in claim 1 further comprising:
- a second terminal; and
- a second power supply node coupled to the second terminal,
- wherein the regulator circuit is coupled to the first power supply node and to the second power supply node, and wherein the first power supply node and second power supply node are power supply nodes of the functional circuit.
14. The apparatus as recited in claim 1 wherein the functional circuitry is coupled such that the voltage is the only voltage supplied to power the functional circuitry.
15. The apparatus as recited in claim 1 wherein the voltage is stable over a range of the input current extending between 5 mA and 15 mA.
16. The apparatus as recited in claim 1 wherein the regulator circuit is coupled in parallel to the functional circuitry between the first power supply node and an output terminal.
17. An apparatus comprising:
- a first circuit including a regulator circuit configured to generate a voltage in response to an input current being supplied to an input terminal, the regulator circuit comprising first and second transistors serially connected at a first node, a gate of the first and second transistors connected to the first node, one of the first and second transistors being an N-channel transistor and one of the first and second transistors being a P-channel transistor, the first and second transistors coupled between the input terminal and a terminal coupled to supply an output current;
- functional circuitry, powered by the generated voltage and configured to generate a signal using the generated voltage, the signal indicative of the input current being supplied to the apparatus;
- an isolation circuit responsive to the signal to supply a representation of the signal across an isolation barrier to an isolation link;
- a resistor coupled between one of the transistors at a second node and the output terminal;
- a capacitor coupled between the input terminal and the second node; and
- a third transistor coupled between the input node and the output node, the third transistor having a gate coupled to the second node.
18. A method comprising:
- receiving an input current on an input terminal coupled to a power supply node;
- generating on the power supply node by a regulator circuit a supply voltage for functional circuitry using the input current;
- generating a signal in the functional circuitry indicative of presence of the input current using the supply voltage; and
- supplying a representation of the signal across a voltage isolation barrier to an isolation link.
19. The method as recited in claim 18 further comprising:
- transmitting the representation of the signal over the isolation link to a receiver circuit coupled to a high voltage driver circuit that is electrically isolated from the input current; and
- generating a control signal for the high voltage driver circuit using the representation of the signal.
20. The method as recited in claim 18 wherein supplying the representation of the signal across the voltage isolation barrier comprises supplying the signal into a primary winding of a transformer to cause energy to be coupled into a secondary winding of the transformer, the primary and secondary windings being separated by the voltage isolation barrier.
21. The method as recited in claim 18 wherein the supply voltage is generated using two or more transistors configured as diodes.
22. The method as recited in claim 18 further comprising supplying the input current to first and second transistors serially connected at a first node, a gate of the first and second transistors connected to the first node, one of the first and second transistors being an N-channel transistor and one of the first and second transistors being a P-channel transistor, the first and second transistors coupled between a terminal to receive the input current and a terminal coupled to supply an output current.
23. The method as recited in claim 22 further comprising providing an electrostatic static discharge resistance as part of the regulator circuit.
24. The method as recited in claim 18 further comprising using an oscillator circuit powered by the voltage generated by the regulator circuit.
25. The method as recited in claim 24 further comprising supplying the voltage generated by the regulator circuit to an oscillator circuit used to generate the oscillating signal.
26. The method as recited in claim 18 wherein the signal is an oscillating signal.
27. The method as recited in claim 18 wherein supplying the representation of the signal across the voltage isolation barrier comprises supplying the signal to a capacitor, the capacitor implementing the voltage isolation barrier.
28. The method as recited in claim 18 further comprising:
- electrically isolating the functional circuitry and the regulator circuit from a receiver circuit coupled to a high voltage driver circuit using a capacitor to capacitively couple the functional circuitry to the receiver circuit.
29. An apparatus comprising:
- an input terminal for receiving an input current and an output terminal for supplying an output current;
- means coupled between the input terminal and the output terminal for generating a voltage on a first node coupled to the input terminal when the input current is present;
- means, powered by the voltage generated by the means coupled between the input terminal and the output terminal, for generating a signal while the input current is being received on the input terminal, the signal indicative of the input current; and
- means for supplying the signal over an isolation link.
30. An apparatus comprising:
- a first circuit including a regulator circuit configured to generate a voltage on a first node coupled to an input terminal in response to an input current being supplied to the first node via the input terminal; and
- functional circuitry, coupled to the first node, the functional circuitry being powered by the voltage and configured to generate a signal in response to the voltage, the signal indicative of whether the input current is being supplied to the apparatus,
- wherein the input current is indicative of a control signal for a driver circuit electrically isolated from the input current.
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Type: Grant
Filed: May 29, 2008
Date of Patent: Oct 14, 2014
Patent Publication Number: 20080315925
Assignee: Silicon Laboratories Inc. (Austin, TX)
Inventors: Donald E. Alfano (Round Rock, TX), Timothy J. Dupuis (Austin, TX), Zhiwei Dong (Austin, TX), Brett E. Etter (Austin, TX)
Primary Examiner: Jessica Han
Application Number: 12/129,039
International Classification: H02M 3/335 (20060101); H02M 3/156 (20060101);